Party-line telephone system.



A. CERDA. PARTYLINE TELEPHONE SYSTEM. APPLICATION FILED JUNE 26, 1908. RENEWED JAN. 3, 1913.

1,093,034. Patented Apr. 14, 1914.

3 SHEETQ-SHEET 1.

COLUMBIA PLANOGRAPN CO., WASHINGTON. D. c.

AJG. OERDA.

PARTY LINE TELEPHONE SYSTEM.

. APPLICATION EILED JUNE 26, mos. RENEWED JAN. a, 1913. 1 93,034.

Patented Apr. 14, 1914.

3 SHBETS-SHEET 2.

26- Ger-02% A. G. CBRDA.

PARTY LINE TELEPHONE SYSTEM.

APPLICATION FILED JUNE 26, 1908. RENEWED JAN. a, 1913. 1,093,034.

Patented Apr. 14, 1914.

3 SHEETS-SHEET 3.

72% 2w 5 Z 2 w W Z COLUMBIA PLANOGRAP" COHWASHMGTON. D c;

UNTTE 'srn'rns rarnn QFFTQJEQ ARTHUR G. GERDA, 0F MORELIA, MEXICO, ASSIGNOR, BY MESNE ASSIGNMENTS, T0

' WALTER MOOERS, OF ARLINGTON, MASSACHUSETTS.

PARTY-LINE TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Apr. 314;, 191%.

Application filed June 26, 1908, Serial No. 440,496. Renewed January 3, 1913. Serial No. 740,039.

T 0 all whom it may concern:

Be it known that I, ARTHUR G. CERDA, of Morelia, Michoacan Mexico, have invented certain new and useful Improvements in Party-Line Telephone Systems, of which the following is a specification.

This invention relates to party line telephone systems and consists in electrically operative devices so arranged and connected that any one of a plurality of branch lines may obtain talking connection with the main line or central station to the exclusion of the other branch lines, and whereby the main line or central station can obtain talking connection with any one of the branch lines to the exclusion of the other branch lines.

The branch lines are all initially connected with the main line so that any branch may signal the central exchange. The operation by a branch line for signaling the central exchange is effected by lifting the receiver from the usual receiver hook. This operatively connects the talking circuit of the operating branch and disconnects the signaling circuit of that branch. It also disconnects all the other branches from the main line so that it is impossible for any other branch to have connection of any kind with the operating branch or with the main line. The direct current which is used for talking is operative for giving the aforesaid talking connection of the operating branch with the main line, the source of this current being in the main line, preferably at the central exchange, and initially connected so that it is available for all the branches. The resistance in the signaling circuits of the several branches is so great that the aforesaid direct current can not operate when the talking circuits of the branch are open; but when a receiver is lifted from the hook in any branch line, the resistance of such branch line is so reduced that the direct current is enabled to operate a device in that branch line which disconnects all the branch lines and otherwise connects the operating branch with the main line. Thus the branches which are initially connected with the main line for signaling are disconnected by the closing of the talking circuit in a branch line and a new connection for tall ing is simultaneously made to connect the operating branch with the main line. The same source of direct current can also be used by an operating branch for restoring all the branches to their initial condition wherein they are all connected for signaling, and such operation is effected by replacing the receiver of the operating branch upon its hook to disconnect the talking circuit. The same source of direct current may be used by the operator in the central exchange for breaking the signaling connection with all the branch lines and for otherwise making connection between the main line and any one of the branch lines, the connection last named being maintained to carry a signaling current from the central exchange to the selected branch line and thereafter for maintaining talking connection between the main line and the selected branch line. The same source of direct current may also be used by the operator at the central exchange for breaking the signaling and talking connection which has been made by the central operator and for restoring the branches to their initial condition. A great advantage in being able to perform all the foregoing functions by a single source of direct current in the main line is that renewal of the battery which furnishes the current may be made at the central exchange. The branch lines do not require any individual batteries, magnetos or other current-generating element, but they operate entirely by current whose source may be located at the central exchange.

The devices by which all the foregoing and some other results are made possible may be located at a common junction where all the branch lines may be connected with the main line, and no apparatus other than the usual transmitter, receiver and signaling device need be located at the subscribers stations. The selecting mechanism controlled by the central operator first cuts out all the branch lines, then connects the main line exclusively with one of the branch line's, thus a placing the main line and the selected branch in communication for signaling and talking. The selected mechanism may be further used by thecentral operator to connect two branch lines of the same party line for intercommunication with each other.

Of the accompanying drawings, which illustrate apparatus for carrying out the present invention: Figure 1 represents a diagram including the electrically operative devices by which the connections are controlled. Fig. 2 is a top plan view of the branch out-outs, the selecting mechanism, and other devices which coiiperate therewith. Fig. 3 represents a vertical section in the plane indicated by line 83 of Fig. 1, the parts being shown in their initial posi tions. Fin. 1 represents a vertical section similar to Fig. 3, showing the selector in operative position for connecting the main line exclusively with one of the branch lines.

Fig. 5 represents a vertical section similar to Figs. 8 and 4t, omitting the selecting mechanism and showing one of the branch c011- trolled devices operatively connected for talking. Fig. 6 is an elevation of a switch for controlling the main line. Fig. 7 represents an elevation of one of the branch-line detents which maintains talking connection. Fig. 8 represents a diagram of an induction coil which forms a part of the device shown by Fig. 7. Fig. 9 represents a top plan view including the elements shown by Fig. 6, and cotiperative elements. Fig. 10 represents a vertical. section in the plane indicated by line 10-10 of Fig. 2. Fig. 11 represents a rear elevation of circuit-controlling devices at the central exchange, said devices being included in Fig. 1. Fig. 12 represents a vertical section in the plane indicated by line 1212 of Fig. 11.

The same reference characters indicate the same parts wherever they occur.

In Fig. 1, the usual switchboard at the central station is shown conventionally at 15 and a source of direct current is indicated at 16. Direct current from 16 is normally connected in the circuit for operating the usual indicator drop or other signaling device (not shown) by which the central operator is notified when a subscriber takes the receiver from the hook. 17 indicates a continuously driven magneto which furnishes alternating current. by which the central operator is enabled to call the sub-- scribers. The central exchange is provided with controlling mechanism indicated as a whole at 18. The apparatus which controls the connections between the main line and the branch lines is indicated as a. whole at 19. The apparatus so designated may be located in a junction box at any convenient place.

For the sake of illustration, the diagram shown by Fig. 1 includes a main line and three branch lines; but it is to be understood that the number of branch lines may be varied as desired. The devices in the junction box 99 are connected with the switchboard 15 by main line conductors 100, 101. The branch-line conductors which connect the junction box with the several subscribers are indicated at 200, 300 and 100 respectively. Each branch line includes a separate cut-out device, the coils of said devices being indicated at 20, 30 and 40. Each cut-out coil is connected in series with its own branch line.

The controlling mechanism at the central exchange is connected to the switchboard15' opens the switch 52 so that both kinds of current cannot be used at the same time.

Direct current 16 is used by the central operator for making connection exclusively with one of the branch lines, and the operation involves the use of 'a selector which is operable by direct current 16. The operation of the selector is effected by sending a predetermined number of impulses of direct current 16. These impulses are sent by a sending switch which is normally open, as shown by Fig. 1. This switch is in a shunt circuit 56 and is operated by an oscillatory vibrator 57. The vibrator is actuated by a toothed wheel 58. The wheel is loosely mounted upon an arbor A hand lever 60, hereinafter termed a controller, is also mounted upon the arbor 59. 61 carried by the lever 60 engages the teeth of the Wheel 58 and is adapted to drive the wheel in one direction and to ride over the teeth when moving in the opposite direction. The controller 60 has a handle 66 of insulating material. By means of this handle the central operator may swing the controller in a clockwise direction .tothe desired position for selecting one of the branch lines, and when the operator releases the controller, a spring 71 returns the controller to its initial position. The first thing which happens when the controller is moved in a clockwise direction is opening the switch 52. Then the pawl 61 rides over the toothed wheel until the movement of the controller is reversed. its initial position, the pawl 61 turns the wheel 58, and the wheel actuates the vibrator 57 which in turn operates the switch to send out impulses of direct current to the junction box 19; The number of impulses thus sent out depends upon the length to which the controller is moved by the operator. insulating material to which are aifixed the independent contact fingers which close the switches 52 and 53 respectively. The controller also carries a contact member 65 and a pin 69. (See Figs. 11 and 12). The contact member 65 is used for closing switch 64, and the pin 69 is used for closing a switch A springpressed pawl As the controller moves back to.

The controller carries a. block 62 of 67. The member 65 is disposed in the handle 66 and is in the form of a plunger. It is adapted to be depressed by one finger of the operators hand, but is normally held in inoperative position by a helical spring shown in Fig. 12. The function of the switch 64 is to send direct current through coil R to restore the selector to its initial position. The pin 69 acts upon a lever 68 when the controller returns to its initial position after sending impulses for selecting. The lever 63 in turn closes the switch 67 and sends an impulse of direct current through the coil at the junction box for the purpose of disconnecting the motor M from the source of current so that the selector cannot be moved beyond the desired position as by another impulse of current.

The circuit controlled by 65 includes 64, 72, 1c, 51, 52, 5o, 15, 100,105,11, c, ground, 107 and 64. The circuit controlled by (37 is as follows: 73, 51, 16, 51, 15, 101, 110, O, 118, ground, 109, 67.

Each branch line comprises a signaling circuit of relatively high resistance and a talking circuit of relatively low resistance. The signaling circuits are indicated at 201, 301 and 401, and each includes a suitable signaling device such as a polarized bell adapted to be operated by alternating cur rent. The talking circuits are indicated at 202, 302 and 402, and each includes the usual transmitter and receiver, and hook for holding the receiver when it is not in use. The receiver hooks are indicated at 203, 303 and 403. These hooks are connected in the usual way so as to close the signaling circuits when they are depressed by the receivers, and to close the talking circuits when the receivers are taken oil". WVhen the receivers are taken off, the hooks are raised by the usual springs (not shown). One side of each branch line is connected with the main line conductor 100 in the junction box 99. The other side of each branch line'is connected to an individual binding post in the junction box, said posts being indicated at 76, 77 and 73. Conductors 21, 31 and 41 extend respectively from the binding posts to stationary contacts 23, 33 and 43 of the automatic cut-out mechanism 19. The return conductors 22, 32 and 42 connect the cut-out mechanism with a common conductor 7 9 bywhich the branch lines are connected with the return conductor 101 of the main line. The cut-out devices 20, and control the connections between the conductors 21, 22, 31, 32 and 41, 42, as hereinafter explained. These cut-out devices are initially connected in series with their respective branch lines by contacts 23, 24, 33, 34, and 43, 44. These stationary contacts are mounted upon a strip 80 of insulating material. The contacts, arranged in pairs, are sepa rated from each other, and electrical connection is made between them by movable contacts 25, 35 and 45, shown in Figs. 2 to The last named contacts are carried by a connector 81 which is common to all the branch lines, this connector being movable in such manner that it will open and close all the b 'anch lines collectively. For convenience it is mounted upon pivots at and is so disposed that its weight causes it to normally connect the branch lines with the main line; and when it is lifted to the position shown by Figs. 4 and 5 it disconnects all the branch lines from the main line.

All the branch lines are initially connected with the switch board 15 at the central exchange by means of the common connector 81 just described. For example, the circuit including the branch 300 is as follows: di rect current 16, conductor 51, switchboard 15, main line conductor 101, conductor 70, conductor 32, cut-out coil 30, 30, contacts 34, 35, 33, conductor 31, binding post 7'7, branch conductor 300, hook 303, signaling circuit 301 including high resistance signaling device, branch conductor 300, main line con.- ductor 100, switchboard, conductor 50, switch 52, conductor 51, direct current 10, The connection between the main line conductors 100, 101, and the circuit 51, is maintained by the usual conductors which include a device for signaling the central operator, and a talking circuit including a listening key for the central operator, this last-named equipment being standard and well-known and omitted from the drawings for the sake of avoiding confusion. The other branch lines 200 and 400 are initially connected with the main line in the same way that the branch 300, just described, is connected. It is apparent, therefore, that direct current 16 is initially connected in the main-line circuit and that it is available for all the branch lines, but it is not effective when its circuit depends upon the high-re sistance signaling means in the branch lines. The effect of the direct current is not shown in any way until the talking circuit of one of the branch lines is closed by its receiver hook. When the talking circuit in any one of the branches is closed, the resistance of the complete circuit is so reduced that a direct current 16 actuates two devices, one of which is the annunciator at the central exchange and the other is the cut-out device in the branch line whose talking circuit has been closed.

Assuming that the talking circuit of branch 300 is closed, the following operation occurs: direct current 16 flows through 51, operators annunciator (not shown), main line 101, conductor 79, conductor 32, cut-out coil 30, 30, contacts 34, 35, 33, conductor 31, binding post 77, branch conductor 300, hook 303, talking circuit 302, branch conductor 300, main line conductor 100, switchboard,

conductor 50, closed switch 52, conductor 51,

direct current 16. The coil 30, 30 of the branch line cut-out causes the operation of a cut-out device which is shown by Figs. 2 to 5. The armature 110 is afiiXed to a tilting lever 111 pivotally mounted at 112. The opposite end of this lever lies under the common connector 81, so that when the armature is attracted the common connector is lifted to inoperative position, thus breaking the circuit between the contacts 33 and 34. It also breaks the connection between contacts 23, 24, and 43, 44, thus disconnecting all the branch lines from the main line. The operating branch 300 is, however, reconnected with the main line by the movement of the tilting lever 111. For this purpose the lever has a contact 115 which cooperates with stationary contacts 38. Contacts 38 are included in a conductor 114 which forms a shunt connection between the conductors 31 and 32. Thus the operation which disconnects all the branches from the main line reconnects the operating branch at 38 so that a talking circuit will be com pleted as follows: direct current 16, conductor 51, switchboard 15, main-line conductor 101, conductor 7 9, conductor 32, conductor 114 including switch 38, conductor 31, binding post 77, branch-line conductor 300, hook 303, talking circuit 302, branch conductor 300, main line conductor 100, switchboard 15, conductor 50, switch 52, conductor 51, direct current 16. The central operator, having been notified by the usual annunciator, can then obtain connection with the branch 300 by closing the customary listening key. (Not shown), The branch 300 may then be connected in the usual way with another main line or with another branch of the same party line, as hereinafter explained.

The other branch lines have switches similar to the switch 38 for reconnecting them with the main line for talking. This switch in the branch 200 is indicated at 28, and a similar switch in the branch 400 is indicated at 48. The connections and devices in the several branches are exact duplicates of each other in every respect.

In order to hold the connection last described, the tilting lever 111 must be locked. in the position to which it is moved by its cut-out coil. For this purpose a detent 116 is provided. (See Fig. 7). This detent has a shoulder adapted to engage the under surface of the lever 111 as shown in Fig. 7 The detent is pivotally mounted upon a suitable support and is provided with a spring 117 by which it is moved to locking position when the armature 110 is attracted. The detent carries an armature 123 which cooperates with the core 124 of an induction coil 39. The induction coil (see Fig. 8) includes a primary winding 127 and a secondary winding 128 whose circuit is closed. The detent 116 remains in locking position so long as the talking circuit of its branch remains closed; but when the talking circuit is opened, as by replacing the receiver on the hook, the full current strength flows through the primary winding 127 and an induced current is set up in the secondary circuit of the winding 128. This induced current magnetizes the core 124 and causes an unlocking movement of the detent 116. The weight of the common connector 81 then causes it to drop to reconnect all the branch lines with the mainline and to return the tilting lever 111 to its initial position.

The primary windings of the several in duction coils 29, 39 and 49 are connected in multiple on one side by a conductor 126 which leads to the main-line conductor 100, and on the other side by conductors 125 which lead to the contacts 23, 33 and 43. The circuit which includes the primary winding 127 is a shunt when a branch talking circuit is closed, and is a' simple circuit when the branch talking circuit is broken. It is as follows: direct current 16, conductor 51, switchboard, 101, 79, 32, 38, 114, '31, 33, 125, 127 of 39, 126, 100, switchboard, 50, 52, 51, 16.

The foregoing explanation relates to the operation whereby a branch line may call the central exchange and-effect talking connection therewith and disconnect all the other branch lines. From this point on, the explanation relates to the operation whereby the central operator may call'the desired branch line and disconnect all theother branch lines. The automatic mechanism at 19 includes a selector 83 which is operable by direct current 16 and controlled exclusively by the central station. This selector is shown in its initial position by Fig. 2, and it is moved step by step in a clockwise direction, and in so moving it first actuates the common connector 81 to disconnect all the branch lines and by continued move lector is mounted upon a pivot pin 84 and is normally held against a stop 86 by a spring 85. The selector is moved step, by step in a clockwise direction by a suitable motor which is operable by direct current 16. The coil of the motor is indicated at M, and the armature m is mounted upon-a lever m. This lever is mounted upon a pivot m and is normally held by a spring m so that it remains against a stop 412/. An actuating pawl. m at the free end of the lever is held by spring in in coiiperative engagement with a toothed wheel 90 which is aflixed to the hub of a selector 83. The desired movement of the selector is effected by sending impulses of direct current through the coil M. In this way the lever m is reciprocated and moves the toothed wheel 90 one tooth at a time. In order to hold the selector at the position to which it is moved by the motor, the selector is provided with another toothed wheel, indicated at 91, the teeth of which are engaged by a retaining pawl 2. This pawl is held againstthe Wheel 91 by a spring 32.

An anti-friction roll 89 near the free end of the selector engages a lip or flange 88 which extends downwardly from the under side of the connector 81. This flange, as shown by Fig. 10, has an inclined portion which causes upward movement of the connector when the selector is moved away from its stop 86. The depth of the flange 88 is uniform throughout the greater part of its length, sothat when it has been raised to inoperative position by the selector it will remain substantially stationary while the selector continues to move. A contact member 87 at the free end of the selector passes between and engages a series of pairs of stationary contacts, the latter corresponding to the several branch lines. The first pair of stationary contacts includes the contact 23, already mentioned, and a contact 26. These contacts establish signaling and talking connection of the main line with the branch line- 100. The second pair of stationary contacts, which controls the branch 300, includes the contact 33, already mentioned, and a contact 36; and the third pair of contacts includes the contact 13 and a contact 41-6. The selector enables the central operator to do substantially what av branch-line user is enabled to do by means of the tilting lever 111. For example, when the central operat-or sends out a certain number of current impulses, the selector will move to a position which places the movable contact 87 between the contacts 33 and 36. Incidentally the contact 87 passes between and touches the contacts 23 and 26, but without causing any result in the branch line 200 because the signaling devices in the branch lines are not operative by direct current but are operative only by alternating current. The selector therefore merely disconnects all the branch lines by lifting the common connector 81, and then reconnects the desired branch with the main line.

The circuit for the motor M includes initially closed switches 27, 37 and 17 which are controlled by the tilting levers 111.

These levers have contact members 113 which touch the stationary contacts of the switches. These switches are connected in series by a contactor 103 one end of which is connected to the motor and the other end to a conductor 102. hen all the branch lines are in their initial condition, the current impulses from the central station traverse the following circuit: direct current 16, conductor 51, switchboard 15, main line 101, conductor 10st, motor M, conductor 103, switches 27, 37, 47, conductor 102, main line 100, switchboard, conductor 50, shunt circuit 56, switch 55, conductor 51, direct current 16. The switch 52 is open when the switch is in operation. When the central operators controller returns to its initial position after having caused the selector to connect the desired branch, the central operator may then operate the signal in the desired branch by depressing the controller 60 below its initial position. The initial position of the controller is determined by a spring 63 which normally keeps the direct-current switch 52 closed for talking. Now when the central operator depresses the controller below its initial position the switch 52 is opened and the switch 53 is closed, thus connecting alternating current 17. The signaling current then traverses the following circuit: generator 17, conductor 54L, conductor 51, switchboard 15, main line 101, conductor 79, conductor 32, shunt 32*, contacts 36, 87, conductor 31, 77, branch conductor 300, hook 303, signaling circuit 301, branch conductor 300, main line 100, switchboard, conductor 50, switch 53, conductor 54:, enerator 17. lVhen the controller 60 is released, the spring 63 lifts it back to its initial position, thus disconnecting the signaling current and reconnecting the talking current. he user of branch 300, having been notified, takes up the receiver as usual, with the result of closing the talking circuit in that branch.

The return of the selector to its initial position is effected by retracting the pawls m and g) from their respective toothed wheels. For this purpose a releasing device is provided, the same consisting of an electro-magnet R, armature r and lever r. The lever is mounted upon a pivot r and is normally held against a stop r by a spring r The armature is mounted on the lever and the lever is so disposed that it will engage both pawls and disengage them from their respective toothed wheels when the armature is attracted by the magnet. The central open ator may send an operating current through the magnet R by pressing the plunger 65 in the handle 66 of the controller. When the plunger 65 engages the contacts 64, direct current flows as follows: from 16, 51, 7 2, 64, 65, 107, ground, 106, R, 105, 100, 15, 50, 52, 51, 16.

Two branch lines of the same party line may be operatively connected with each other for talking through the agency of the central operator. For example, the user of branch 300 calls the central station as hereinbcfore explained, and requests the central operator to make connection with the branch 1-00. It will be remembered that all the branches except the operating branch have been disconnected by the calling operation of the operating branch. While the calling branch remains connected by its switch 38, the central operator sends out the required number of impulses of direct current 10 to move the selector 83 to the position which will place the contact 87 between the contacts 13 and 4:0. The central operator then depresses the controller 60 so as to send alternating current through the branch 400 which is now connected by the selector. \Vhen the user of the branch line 100 takes the receiver from the hook, the talking circuits of the branch lines 300 and 4.00 are connected with each other so as to utilize the direct current 16 for talking.

The motor circuit previously described includes a shunt circuit 103 in which switches 27, 37 and 417 are arranged in series. It is obvious, therefore, that this shunt circuit is opened whenever any one of the branch lines calls the central station, because such operation causes a movement of the tilting lever 111 in the branch whose talking circuit is closed. Now, therefore, in order to operate the motor to select another branch after one branch has called, the motor circuit is provided with ashunt circuit 108 which includes a switch A. This switch (see Fig. 6) comprises two stationary contacts and a movable contact a. The switch is initially open as shown by Figs. 2 and 6, and the motor circuit is initially closed through the shunt circuit 103. The movable switch member a is mounted upon a pivot a and is connected by a link 0 with a lever 0 which is mounted upon a pivot 0 An ear 0 is afiixed to the link 0 in position to be engaged by the releasing lever T when the latter is moved to disengage the pawls from the toothed wheels 90 and 91. \Vhenever the user of one branch line calls the central station, the shuntcircuit 103 is broken, so that the central operator cannot send the current through that shunt circuit for operating the motor. Now if it should be necessary to connect the calling branch with one of the other branches of the same party line, the central operator must first complete the shunt circuit 108 by closing the switch A. This is done by depressing the plunger at the central station to send direct current through the coil R. As the selector is at this time in its initial position, it will not be moved; but the lever o will nevertheless be actuated by the magnet R so that the movement will be transmitted to the movable contact a, which will then be placed between the stationary contacts of the switch A. 'The central operator may then send out impulses of direct current through the motor circuit, which is the same as that hereinbefore described with the ex ception of the shunt circuit 108 being substituted for the shunt circuit 103.

The switch A is opened automatically whenever the selector returns to its initial position. For this purpose the contact mem her a is provided with an extension a and the toothed wheel 90 is provided with a stud 120 which carries a relatively stiff spring 121. The free end of this spring is arranged to engage and move the extension a? during 7 coil is controlled by the switch 67 (Fig. 11)

hereinbefore described. This magnet O performs its function by opening the switch A. The armature for the magnetis indicated at 0, and it is mounted upon the lever 0 (See Fig. 6). The function of the magnet O is the opposite of the function ofthe magnet R, the first-named magnet opening the switch A and the other magnet closing the switch A. An operating current is sent through the magnet 0 each time the central operators controller completes the desired number of current impulses for the motor. Referring to Fig. 11, as the controller descends, the pin 69 carried thereby engages the lever 68, moving the latter and thereby closing the switch 67. Direct current then traverses the following circuit: 16, 51, 15, 101, 119, O, 118, ground, 109, 67, 73, 51, 16. This opens the switch A. and disconnects the motor from the source of current. The motor cannot thereafter be operated unless all the switches '27, 37 and 47 in the shunt circuit 103 are closed, or unless the magnet R is energized to release the selector so that it may return to its initial position.

As means for enabling the central operator to stop thecontroller 60 at the desired position for sending out current impulses, a gage 70 isprovided, the same being concentric with relation to the axis of the controller. This gage is provided with holes 172, 17 3 and 174. which correspond respectively with the branch lines 200, 300 and The r 400. The central operator can insert any convenient instrumentality, such as a pencil, in the hole corresponding to the branch which is to be selected. Then the controller may be moved until it strikes the pencil or other instrumentality, the latter limiting the preliminary movement of the controller so that the desired number of current impulses is determined before the controller begins to cause such impulses.

In Fig. 1 the branch 200 includes a device for indicating that the branch is connected or disconnected. Each branch may be provided with a similar device, but this one is sufficient to show the principle involved. A shunt circuit including the primary winding 0 of an induction coil is connected to the two main conductors of the branch. A secondary winding 0 and an electromagnet 0 are included in series in a closed circuit. A visual indicator 0 mounted on a pivot 0 carries an armature 0 which cooperates with the magnet 0 When a current is induced in the secondary circuit by the disconnecting of the branch 200, the indicator is thrown to one side; and when a current is induced by connecting the branch, the indicator is thrown to the other side.

I claim- 1. In a telephone system comprising a party line having a plurality of branches initially connected therewith, and a central station subject to call by any of the branches, means cont-rolled by a calling operation for severing the connections in all of the branches when one branch calls, said means otherwise making connection with the calling branch so long as the talk ing circuit of that branch remains closed.

2. In a telephone system comprising a party line having a plurality of branches initially connected therewith, and a central station subject to call by any branch, a normally inefiective cut-out in each branch adapted to discontinue all the branches and otherwise close the branch with which it is associated, said cut-out being operative by insertion of the talking circuit of the calling branch.

3. In a telephone system comprising a party line having a plurality of branches, and a central station subject to call by any branch, an electrically actuated cutout operable by current in the talking circuit of the calling branch for cutting out all the other branches, and a normally operative detent for holding the cut-out in operative position, said detent being subject to re traction when the said talking circuitis opened.

l. In a telephone system con'iprising a party line having a plurality of branches, and a central station subject to call by any branch, a normally closed cut-out operable by the closing of the talking circuit of a calling branch, said cut-out efiecting severance of the other branches and of its own conductor, and a normally operative detent for holding the cut-out in operative position, said detent being subject to retraction by opening the talking circuit of the calling branch.

in a. telephone system comprising a main line and a plurality of branches, electrically controlled means for selecting a branch, and controlling means comprising a manually ope 'ative controller movable from a normal position in din erent paths, means for governing the selecting means operable by the controller when the latter moves in one path to normal position, and a signaling switch so arranged as to be closed by the controller when the latter is moved away from normal position in another path.

6. A telephone system comprising a main line including a source of direct current, a plurality of branch lines, and means for initially connecting said branch lines with said main line, each of said branch lines having means operable by said current for moving said connecting means to disconnect all said branch lines and for reconnecting the oper ating branch line with the main line.

7. A telephone system comprising a main line having a source of direct current, a plurality of branch lines, means for initially connecting said branch lines with said main line, each of said branch lines having means operable by said current for moving said connecting means to disconnect all said branch lines and for reconnecting the oper ating branch line with the main line for talking.

S. A telephone system comprising a main line having a source of direct current, a plurality of branch lines initially connected therewith, each of said. branch lines having means operable by said current for disconnecting all the branch lines and reconnecting a calling branch line with the main line.

9. A telephone system comp-rising a main line and a plurality of branch lines initially connected therewith, said main line having a source of direct current, each of said branch lines having means operable by said current for disconnecting all the branch lines and for reconnecting a calling branch line with the main line for talking.

10. A telephone system comprising a main line having a source of direct current, a plurality of branch lines initially connected with the main line, and means operable by said current for disconnecting all the branch lines and reconnecting one of said branch lines with the main line for talking.

11. A telephone system comprising a main line and a plurality of branch lines initially connected therewith, said main line including a source of direct current, and means in each branch line and operable by said current for disconnecting all the branch lines and for otherwise connecting one of said branch lines with the main line.

12. A telephone system comprising a main line and a plurality of branch lines initially connected therewith, said main line including a source of direct current, and means in the main line and operable by said current for disconnecting all the branch lines and for reconnecting the main line with any one of said branch lines.

18. A telephone system comprising a main line and a plurality of branch lines initially connected therewith, said main line including a source of direct current, and means in the main line and operable by said current for disconnecting all the branch lines and for reconnecting the main line successively with said branch lines.

14. A telephone system comprising a main line having a source of direct current, a plurality of branch lines initially connected with the main line, and means in the main line and operable by said current for disconnecting all said branch lines, and otherwise connecting said branch lines one at atime with the main line.

15. A telephone system comprising a main line and a plurality of branch lines, means initially connecting all said branch lines with said main line, means operable by the main line for moving said connecting means to disconnect all said branch lines from the main line and for reconnecting the main line with any one of said branch lines, and means in eachof said branch lines for moving said initial connecting means to disconnect all said branch lines and for reconnecting an operating b 'anch line with the main line.

16. A telephone system comprising a main line having a source of direct current, a.

plu 'ality of branch lines initially connected with the main line, and means in the main line and operable by said current for disconnecting all said branch lines and reconnecting any one of them with the main line, each of said branch lines having means operable by said current for disconnecting all said branch lines and reconnecting an operating branch with the main line.

17. A telephone system comprising a main line and a plurality of branch lines initially connected therewith, each of said branch lines including an initially open talking circuit, a source of direct current in the main line, and means operable by said current upon closing the talking circuit of any one of said branch lines for disconnecting all said branch lines and reconnecting the operating branch lines with the main line.

18. A telephone system comprising a main line, a plurality of branch lines initially connected therewith, a source of direct current in said main line, an initially open switch in each of said branch lines for con necting said branch lines separately with the main line, means in each branch line for disconnecting all the branch lines and for closing the switch in the operating branch line, means for locking said switch in closed position, and means operable by said current for actuating said'locking means to release said switch.

19. A telephone system comprising a main line having a source of direct current, a plurality of branch lines initially connected therewith, each of said branch lines having means operable by said current for disconnecting all said branch lines and reconnecting an operating branch line with the main line, means for locking each of said reconnecting means in operative position, and means operative by said current for moving said locking means to release said reconnecting means.

20. A telephone system comprising a main line having a source of direct current, a plurality of branch lines initially connected therewith, each branch line having operating means operable by said current for dis connecting all said branch lines and reconnecting the operating branch line, means for locking said operating means in operative position, and means operative by said current for moving said locking means to release said operating means.

21. A telephone system comprising a main line having a source of direct current, a plurality of branch lines initially connected with the main line, the talking circuit of each of said branch lines being initially open, each of said branch lines having operating means operable by said current upon closing the talking circuit therein for disconnecting all the branch lines and reconnecting the operating branch line, with the main line, means for locking said operating means in operative position, and means in each branch line and operative by said current upon opening the talking circuit of the operating branch line for causing said looking means to release said operating means.

22. A telephone system comprising'a main line having a source of direct current, a plurality of branch lines initially connected with the main line, and means operable by said current upon losing the talkingccircuit of any one of said branches for disconnecting all said branch lines and for reconnecting the operating branch line with the main line. 7

23. A telephone system comprising a main line having a source of direct current, a plurality of branch lines initially connected ,Wltll said main line, means operable by said current upon closing the talking circuit of In testimony whereof I have aflixed my one of sald branch hnes for disconnectlng s1gnature,1n presence of two Witnesses.

all the other branch lines, and means in each ARTHUR G. CERDA. branch line and operable by said current fer Witnesses:

5 indicating Whether the branch line is con- 0. F. BROWN,

nected or disconnected. P. W. PEZZETTI.

Copies of this patent may be bbtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

